What is the difference between partially and totally failed conference call?

Totally failed conferences occur when no connections is successfully established between any participant in a conference. Which usually indicates that the participants attempted to join, but were unable to join the conference but due to various types of errors: Media source related, Negotiation related, Firewall/NAT related.

Partially failed conferences occur when connections for some participants fail to establish, meanwhile succeed for others, this is most likely to occur in multi-party (more than 2 participants) conferences, because in a two-party call, if one person fails to join the conference is categorized as failed.